1. Field of the Invention
The present invention relates to semiconductor processing, and more particularly, to a process for treating an apparatus such as a furnace used in producing a high-k dielectric metal-containing insulator.
2. Description of the Related Art
High dielectric constant (high-k) materials with low equivalent oxide thickness (EOT) and very low leakage currents are likely to replace silicon dioxide (e.g., SiO2) dielectric layers in the semiconductor industry. High-k metal-oxides can provide the required capacitance at a considerably larger physical thickness than SiO2, thus allowing the reduction of the gate leakage current by suppression of direct tunneling. Binary oxides such as hafnium oxide (e.g., HfO2) and zirconium oxide (e.g., ZrO2), metal-silicates such as hafnium silicate (e.g., HfxSiyOz) and zirconium silicate (e.g., ZrxSiyOz), alumina (e.g., Al2O3), and lanthanide oxides, are promising metal-oxide high-k materials for gate stack applications.
Precise control of the high-k film growth, the evolution of the interface between the silicon and the high-k film, and the thermal stability of the gate stack are key elements in the integration of high-k films into semiconductor applications. More specifically, hafnium silicate (e.g., HfxSiyOz) films are being developed as high-k dielectrics to scale transistor gate performance beyond thin SiO2.
In some cases, multiple film materials are processed in the same thermal chamber or furnace. Dry cleaning of the furnace is required to maintain practical usage of the tool. Various parts of a processing system can include consumable or replaceable system components that can, for example, be fabricated from quartz, silicon, alumina, carbon, or silicon carbide. The consumable nature of the replaceable components requires frequent maintenance of the processing system. Consumable system parts are commonly replaced or cleaned after film accumulation threatens particle problems, for example between incompatible processes scheduled to be run in sequence, or after detrimental processing conditions, or when unsatisfactory processing results are observed. Alternately, consumable system parts can be cleaned or replaced according to a predetermined maintenance schedule that can, for example, be based on the number of operating hours.
Chamber conditioning processes (also referred to as passivation processes) are commonly implemented in semiconductor fabrication to prepare process chambers for optimal performance. For example, chamber conditioning processes may be carried out following chamber cleaning, after an extended chamber idle period, or before a first chamber production process. When used with plasma chambers, chamber conditioning processes typically involve using a “conditioning plasma” in the plasma chamber for a predetermined length of time to prepare or “condition” the chamber for the upcoming performance of a plasma process involving production wafers. The parameters of the conditioning process (e.g., RF power, chamber and substrate temperature, feed gas composition, and pressure) are usually maintained at or near the parameters of the corresponding production process for which the chamber is being conditioned. In this manner, conditioning processes can help ensure that all processes performed in a process chamber produce results within a desired range.
A method of pre-coating the quartz walls with an SiO2 deposition has been utilized previously to reduce the damage to the quartz parts from dry etching and prevent early quartz failure and particle generation. These methods, however, do not provide the requisite degree of cleaning for long term operation of the furnaces and maintenance of a low particulate process in a hafnium oxide, hafnium silicate, or hafnium oxynitride deposition system.